In Massachusetts, you can not use an altered or restored plate and the RMV can reject the use of a particular plate if the paint is not in good enough condition. Gotta love us liberal Massholes. No not really
The only reason a weld would crack is if the person who had welded it for you did not use the proper cast iron rod. I have seen this in all areas of fabrication through the years. "Look, I used the mig and it's holding fine". Thats when i would whack whatever it was with a hammer or mallet to...
I couldn't tell you how much brazing rod I've ground through getting to the problems on my buddy's 31 pickup. Can we say it was obvious that a plummer owned the car.